Light-scattering substrate, method of manufacturing the same, organic light-emitting display device including the same, and method of manufacturing the organic light-emitting display device

ABSTRACT

A light-scattering substrate which can be thinned and has improved thermal resistance, a method of manufacturing the same, an organic light-emitting display device including the same, and a method of manufacturing the organic light-emitting display device are disclosed. The light-scattering substrate includes a light-scattering layer composed of a plurality of metal nanoparticles which are attached to at least a surface of a substrate. The metal nanoparticles are formed by agglomeration of a metal on the substrate, and show a surface plasmon phenomenon.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 from an applicationearlier filed in the Korean Intellectual Property Office on Dec. 6, 2010and there duly assigned Serial No. 10-2010-0123603.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-scattering substrate, a methodof manufacturing the same, an organic light-emitting display deviceincluding the same, and a method of manufacturing the organiclight-emitting display device. More particularly, the present inventionrelates to a light-scattering substrate which can be thinned and whichhas improved thermal resistance, a method of manufacturing the same, anorganic light-emitting display device including the same, and a methodof manufacturing the organic light-emitting display device.

2. Description of the Related Art

The recent trend toward larger displays is increasing interest in auniformly bright screen, and a key factor in achieving a uniformlybright screen is scattering. Many display devices use a light-scatteringsheet or film to effectively utilize a light source.

A light-scattering film causes light incident in a certain direction tospread in various directions. A light-scattering film typically includesa polymer film and light-scattering particles inserted into the polymerfilm. To achieve light-scattering characteristics, attempts are beingcontinuously made to control the refractive index, the size, and theshape of the light-scattering particles. However, due to thelight-scattering particles, the light-scattering film should be formedto a thickness of approximately 5 to 10 μm so as to achieve a desiredlevel of light-scattering characteristics. Thus, it is difficult to thinthe light-scattering film. In addition, if the light-scattering film ismade of a conventional plastic film having low thermal resistance, itscharacteristics may deteriorate when the plastic light-scattering filmis exposed to a subsequent process for forming thin-film transistors(TFTs) during the manufacturing of a display device.

SUMMARY OF THE INVENTION

The present invention provides a light-scattering substrate which can bethinned and which has improved thermal resistance.

The present invention also provides a method of manufacturing thelight-scattering substrate.

The present invention further provides an organic light-emitting displaydevice including the light-scattering substrate.

Finally, the present invention provides a method of manufacturing theorganic light-emitting display device.

However, aspects of the present invention are not restricted to the onesset forth herein. The above and other aspects of the present inventionwill become more apparent to one of ordinary skill in the art to whichthe present invention pertains by referencing the detailed descriptionof the present invention given below.

According to an aspect of the present invention, a light-scatteringsubstrate comprises a light-scattering layer composed of a plurality ofmetal nanoparticles which are attached to at least a surface of asubstrate, wherein the metal nanoparticles are formed by agglomerationof a metal on the substrate and show a surface plasmon phenomenon.

According to another aspect of the present invention, a method ofmanufacturing a light-scattering substrate includes: forming a metalthin film on a substrate; and forming a light-scattering layer composedof metal nanoparticles by annealing the metal thin film to agglomerate ametal of the metal thin film into the metal nanoparticles.

According to another aspect of the present invention, an organiclight-emitting display device comprises: a first light-scattering layercomposed of metal nanoparticles which are attached to a surface of atransparent substrate; a buffer layer formed on the substrate to containthe metal nanoparticles; an active layer formed on the buffer layer andincluding a channel region and source and drain regions; a gateinsulating film formed on the substrate and the active layer; a gateelectrode formed on the gate insulating film so as to overlap thechannel region; an interlayer insulating film formed on the gateinsulating film so as to cover the gate electrode and including contactholes which expose predetermined regions of the source and drainregions, respectively; source and drain electrodes formed on theinterlayer insulating film and connected to the source and drainregions, respectively, by the contact holes; a passivation layer formedon the interlayer insulating film so as to cover the source and drainelectrodes; a first electrode formed on the passivation layer andconnected to any one of the source and drain electrodes; and a pixeldefined layer formed on the passivation layer and exposing apredetermined region of the first electrode.

According to another aspect of the present invention, an organiclight-emitting display device comprises: an active layer formed on asubstrate and including a channel region and source and drain regions; agate insulating film formed on the substrate and the active layer; agate electrode formed on the gate insulating film so as to overlap thechannel region; an interlayer insulating film formed on the gateinsulating film so as to cover the gate electrode and including firstcontact holes which expose the source and drain regions, respectively;source and drain electrodes formed on the interlayer insulating film andconnected to the source and drain regions, respectively, by the firstcontact holes; a passivation layer formed on the interlayer insulatingfilm and including a second contact hole which exposes any one of thesource and drain electrodes; a first electrode formed on the passivationlayer and connected to any one of the source and drain electrodes by thesecond contact hole; a pixel defined layer formed on the interlayerinsulating film and exposing a predetermined region of the firstelectrode; an organic light-emitting layer formed on the predeterminedregion of the first electrode which is exposed by the pixel definedlayer; a transparent second electrode formed on the pixel defined layerand the organic light-emitting layer; and a light-scattering layercomposed of a plurality of metal nanoparticles which are attached to atop surface of the second electrode.

According to another aspect of the present invention, a method ofmanufacturing an organic light-emitting display device comprises:forming a plurality of metal particles attached to a transparentsubstrate by stacking a metal thin film on the substrate and annealingthe metal thin film to agglomerate a metal of the metal thin film; andforming a buffer layer on the substrate to contain the metal particles.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a cross-sectional view of a light-scattering substrateaccording to an exemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view of a light-scattering substrateaccording to another exemplary embodiment of the present invention;

FIG. 3 is a flowchart illustrating a method of manufacturing alight-scattering substrate according to an exemplary embodiment of thepresent invention;

FIGS. 4 thru 6 are cross-sectional views respectively illustratingprocesses in the method of manufacturing a light-scattering substrateaccording to the exemplary embodiment of the present invention;

FIG. 7 is a cross-sectional view of an organic light-emitting displaydevice according to an exemplary embodiment of the present invention;

FIG. 8 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention;

FIG. 9 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention;

FIG. 10 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention;

FIG. 11 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention;

FIGS. 12 thru 23 are cross-sectional views respectively illustratingprocesses in a method of manufacturing an organic light-emitting displaydevice according to an exemplary embodiment of the present invention;and

FIG. 24 is a graph illustrating haze with respect to the thickness of alight-scattering layer of a light-scattering substrate according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Advantages and features of the present invention and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of exemplary embodiments and theaccompanying drawings. The present invention may, however, be embodiedin many different forms and should not be construed as being limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the concept of the invention to those skilled in the art, and thepresent invention will only be defined by the appended claims. In thedrawings, sizes and relative sizes of layers and regions may beexaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on” another element or layer, the element or layer can bedirectly on another element or layer or intervening elements or layersmay also be present. In contrast, when an element is referred to asbeing “directly on” another element or layer, there are no interveningelements or layers present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

Spatially relative terms, such as “below”, “beneath”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe the relationship of one element or feature to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation, in addition tothe orientation depicted in the figures. Like reference numerals referto like elements throughout the specification.

Embodiments of the invention are described herein with reference toplanar and cross-section illustrations which are schematic illustrationsof idealized embodiments of the invention. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerance are to be expected. Thus, embodiments of theinvention should not be construed as limited to the particular shapes ofregions illustrated herein but are to include deviations in shapes whichresult, for example, from manufacturing. Thus, the regions illustratedin the figures are schematic in nature and their shapes are not intendedto illustrate the actual shape of a region of a device, and are notintended to limit the scope of the invention.

Hereinafter, exemplary embodiments of the present invention will bedescribed in further detail with reference to the accompanying drawings.

A light-scattering substrate according to an exemplary embodiment of thepresent invention will now be described with reference to FIG. 1.

FIG. 1 is a cross-sectional view of a light-scattering substrateaccording to an exemplary embodiment of the present invention.

Referring to FIG. 1, the light-scattering substrate 100 according to theexemplary embodiment of the present invention includes alight-scattering layer 120 formed on a substrate 110.

The substrate 110 may be a silicon substrate, a silicon-on-insulator(SOI) substrate, a gallium arsenic substrate, a silicon germanium (SiGe)substrate, a ceramic substrate, a quartz substrate, or a glass substratefor displays. Any substrate for displays can be used as the substrate110. In addition, the substrate 110 may be formed of a material or amixture of materials selected from the group consisting of cellulosederivatives such as cellulose triacetate (TAC), polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polyester resinsuch as polyester acrylate, polysulfone resin such as polyethersulfone(PES), polyetherketone resin such as polyetherketone (PEK),polyetheretherketone (PEEK), polycarbonate resin, polyolefin acrylicresin, styrene resin, and a copolymer of these materials.

The substrate 110 may be formed to a thickness of 10 to 100 nm. Thesubstrate 110 formed to a thickness in the above range contributes tothe thinning of the light-scattering substrate 100 and providesappropriate strength to the light-scattering substrate 100.

The light-scattering layer 120 is formed on the substrate 110 and iscomposed of a plurality of metal nanoparticles.

The metal nanoparticles are attached to an upper surface of thesubstrate 110. Here, the metal nanoparticles may not necessarily coverthe entire surface of the substrate 110, exposing part of the substrate110. The light-scattering layer 120 according to the current exemplaryembodiment is not in the form of a sheet or film into whichlight-scattering particles have been inserted. Instead, a plurality ofmetal nanoparticles attached onto the substrate 110 form thelight-scattering layer 120. Therefore, no film or sheet foraccommodating the metal nanoparticles is required, thus contributing tothe thinning of the light-scattering substrate 100.

The metal nanoparticles can have any shape such as a circular, oval oramorphous shape. Also, they may overlap each other in multiple layers.

The metal nanoparticles may have a diameter of 50 to 500 nm. Sine themetal nanoparticles are not uniform in diameter, the diameter denotes anaverage diameter. When the diameter of the metal nanoparticles is in theabove range, the thinning of the light-scattering substrate 100 can beachieved. Furthermore, light-scattering efficiency can be improved,which, in turn, makes a display screen have uniform brightness and highluminance.

The metal nanoparticles may be formed using metal which shows a surfaceplasmon phenomenon. Metals showing the surface plasmon phenomenon easilyemit electrons in response to an external stimulus and have a negativedielectric constant. Specifically, the metal nanoparticles may be madeof a metal or a mixture of metals selected from the group consisting ofCu, Ni, Co, Fe, Zn, Ti, Cr, Ag, Au, Pt, Al, Pd, and an alloy of thesemetals. If possible, the metal nanoparticles may be made of Ag or Au,which exhibits superior light-scattering properties and surfacestability, or an alloy of Ag or Au and one or more of Cu and Pd.

Surface plasmons refer to quasiparticles which describe the collectiveoscillation of free electrons at the surface of a metal. In the currentexemplary embodiment, light arriving at the surface of the metalnanoparticles which shows the surface plasmon phenomenon causes themetal nanoparticles to oscillate. In so doing, the light is scattered.

The metal nanoparticles are formed by agglomeration of a metal coated onthe substrate 110. The agglomeration of the metal may result in partialexposure of the substrate 110.

The agglomeration of the metal may be caused by an annealing process.Therefore, the metal nanoparticles may be made of a metal which canagglomerate on the substrate 110 during the annealing process due to itshigh surface energy, among metals showing the surface plasmonphenomenon. Specifically, the metal nanoparticles may be made of Ag, Au,a mixture of Ag and Au, or an alloy of Ag or Au and one or more of Cu,Ni, Co, Fe, Zn, Ti, Cr, Pt, Al and Pd. Here, the Ag or Au may be addedat 80 wt % or more based on a total weight of the alloy. When added at80 wt % or more, the Ag or Au can agglomerate into metal nanoparticlesand exhibit a superior light-scattering effect.

The light-scattering layer 120 according to the current exemplaryembodiment is advantageous to the thinning of the light-scatteringsubstrate 100 since it is formed not by the insertion of metalnanoparticles into a sheet or film, but by the agglomeration of metalparticles on the substrate 110. Since no film or sheet is used, thethermal resistance of the light-scattering layer 120 can be improved. Inparticular, when the substrate 110 is made of glass, silicon or quartzinstead of plastic, the thermal resistance of the light-scatteringsubstrate 100 can be further improved.

Hereinafter, a light-scattering substrate according to another exemplaryembodiment of the present invention will be described with reference toFIG. 2.

FIG. 2 is a cross-sectional view of a light-scattering substrate 200according to another exemplary embodiment of the present invention.

Referring to FIG. 2, the light-scattering substrate 200 according to thecurrent exemplary embodiment has the same configuration as thelight-scattering substrate 100 of FIG. 1, except that it includesmultiple light-scattering layers and transparent conductive layers. Thefollowing description will focus on these differences, and elementssubstantially identical to those of the previous embodiment areindicated by like reference numerals, and thus a detailed descriptionthereof will be omitted.

Referring to FIG. 2, the light-scattering substrate 200 according to thecurrent exemplary embodiment includes a substrate 110, a firsttransparent conductive layer 230, a second transparent conductive layer210, a first light-scattering layer 220, and a second light-scatteringlayer 240.

The first transparent conductive layer 230 may be formed on the secondtransparent conductive layer 210 and the first light-scattering layer220, and the first light-scattering layer 220 may be contained in thefirst transparent conductive layer 230. The first transparent conductivelayer 230 maximizes the light-scattering effect of metal nanoparticlesof the first light-scattering layer 220, and prevents the metalnanoparticles from agglomerating again when a subsequent process isperformed at a high temperature.

The first transparent conductive layer 230 may be made of anytransparent material which gives conductivity. If possible, the firsttransparent conductive layer 230 may be made of a material superior intransparency, conductivity and thermal resistance, such as indium tinoxide (ITO), indium zinc oxide (IZO), ZnO or In₂O₃.

The first transparent conductive layer 230 may be formed to a thicknessof 1 to 50 nm. When formed to a thickness in the above range, the firsttransparent conductive layer 230 can further improve thelight-scattering effect and add heat-resisting properties to alight-scattering sheet.

The second transparent conductive layer 210 may be formed between thesubstrate 110 and the first light-scattering layer 220. The secondtransparent conductive layer 210 maximizes the light-scattering effectof the metal nanoparticles, gives heat-resisting properties to thelight-scattering substrate 200, and increases the adhesion of the firstlight-scattering layer 220 to the substrate 110.

The second transparent conductive layer 210 may be made of anytransparent material which gives conductivity. If possible, the secondtransparent conductive layer 210 may be made of a material superior intransparency, conductivity, and thermal resistance, such as ITO, IZO,ZnO or In₂O₃. The second transparent conductive layer 210 can be omittedas desired by those of ordinary skill in the art.

The light-scattering substrate 200 shown in FIG. 2 includes twotransparent conductive layers and two light-scattering layers. However,the present invention is not limited thereto. For example, the firsttransparent conductive layer 230 may be formed on the firstlight-scattering layer 220 so as to contain the first light-scatteringlayer 220, and the second light-scattering layer 240 may be formed onthe first transparent conductive layer 230. By repeating this process, alight-scattering substrate having a plurality of light-scattering layersmay be formed. The plurality of light-scattering layers further improvesthe light-scattering effect of the light-scattering substrate.

As described above, there is no need to insert a film or sheet into alight-scattering substrate according to the present invention, and thisabsence of a film or sheet makes the thinning of the light-scatteringsubstrate possible. Furthermore, the light-scattering substrate offersbetter thermal resistance than conventional films or sheets.

Hereinafter, a method of manufacturing a light-scattering substrateaccording to an exemplary embodiment of the present invention will bedescribed with reference to FIGS. 3 and 4 thru 6.

FIG. 3 is a flowchart illustrating a method of manufacturing alight-scattering substrate according to an exemplary embodiment of thepresent invention; and FIGS. 4 thru 6 are cross-sectional viewsrespectively illustrating processes in the method of manufacturing alight-scattering substrate according to the exemplary embodiment of thepresent invention.

Referring to FIG. 3, the method of manufacturing a light-scatteringsubstrate according to the current exemplary embodiment includes forminga metal thin film (operation S10), performing an annealing process(operation S20), and forming a transparent conductive layer (operationS30).

Referring to FIG. 4, a metal thin film 320 is formed on a substrate 310in the forming of the metal thin film (operation S10).

Specifically, the metal thin film 320 is deposited on at least a surfaceof the substrate 310 by sputtering, chemical vapor deposition (CVD), orthe like.

The substrate 310 may be a silicon substrate, an SOI substrate, agallium arsenic substrate, an SiGe substrate, a ceramic substrate, aquartz substrate, or a glass substrate for displays. Any substrate fordisplays can be used as the substrate 310. The substrate 310 may also bemade of resin. If possible, resin having superior thermal resistance,such as TAC, may be used.

The metal thin film 320 may be formed on at least a surface of thesubstrate 310. The metal thin film 320 may also be formed on bothsurfaces of the substrate 310.

The metal thin film 320 may be made of Ag, Au, a mixture of Ag and Au,or an alloy of Ag or Au and one or more of Cu, Ni, Co, Fe, Zn, Ti, Cr,Pt, Al and Pd. Since Ag or Au has a high surface energy, it mayagglomerate together during annealing and may show the surface plasmonphenomenon. Specifically, the metal thin film 320 may be made of analloy of Ag, Pd, and Cu. Here, the Ag may be added at 80 wt % or morebased on a total weight of the alloy.

The metal thin film 320 may be formed to a thickness of 100 to 200 Å.When formed to a thickness in the above range, metal particles of themetal thin film 320 may agglomerate into metal nanoparticles in theperformance of the annealing process (operation S20), therebycontributing to the thinning of a light-scattering substrate.

Referring to FIG. 5, the metal thin film 320 is annealed in theperformance of the annealing process (operation S20). As a result, alight-scattering layer 330 composed of metal nanoparticles is formed.

Specifically, the metal thin film 320 is annealed to agglomerate themetal particles therein into a plurality of metal nanoparticles attachedonto the substrate 310.

When the metal thin film 320 is heated, Ag or Au having a high surfaceenergy agglomerates with its ambient particles to form metalnanoparticles. The metal nanoparticles have various sizes and shapes.When light reaches the metal nanoparticles attached onto the substrate310, the metal nanoparticles scatter the light due to the surfaceplasmon phenomenon.

As the thickness of the metal thin film 320 increases, the diameter ofthe metal nanoparticles tends to increase. In addition, under the sameconditions, the metal thin film 320 tends to be formed into metalnanoparticles having a greater diameter when made of pure metal thanwhen made of an alloy. Specifically, when metal nanoparticles are formedby depositing and annealing pure Ag, the area of a region of asubstrate, which is exposed by the agglomeration of Ag, is relativelylarge. However, when metal nanoparticles are formed by depositing andannealing an alloy of Ag, Pd and Cu, Pd or Cu acts to hinder theagglomeration of Ag, thereby reducing the area of a region of thesubstrate which is exposed. An increase in the diameter of the metalnanoparticles results in higher haze. However, those of ordinary skillin the art can adjust the diameter of the metal nanoparticles byselecting a metal material in view of a desired haze level.Specifically, the metal nanoparticles may be formed to an averagediameter of 50 to 500 nm. The metal nanoparticles have high haze valuesin the above diameter range.

The annealing process may be performed using a thermal annealing methodusing a furnace, a laser annealing method, or a rapid thermal annealing(RTA) method. In addition, the annealing process may be performed at atemperature of 200 to 350° C. for one hour in the atmosphere of an inertgas such as air or nitrogen. The conditions under which the annealingprocess is performed can be arbitrarily changed by those of ordinaryskill in the art. If possible, however, the annealing process may beperformed at a temperature of 200 to 350° C. In the above temperaturerange, metal particles can agglomerate actively without affecting otherproperties of the substrate 310. As described above, thelight-scattering layer 330 according to the current exemplary embodimentis composed of metal nanoparticles formed by annealing the metal thinfilm 320 on the substrate 310, instead of inserting metal nanoparticlesinto a film or sheet. The light-scattering layer 330 thus formed cancontribute to the thinning of the light-scattering substrate and improvethe thermal resistance of the light-scattering substrate.

Referring to FIG. 6, in the formation of the transparent conductivelayer (operation S30), a transparent conductive material is deposited onthe substrate 310 so as to form a transparent conductive layer 340containing the metal nanoparticles.

Specifically, a transparent material having superior conductivity, suchas ITO or IZO, is deposited on the substrate 310 and thelight-scattering layer 330 by, e.g., CVD, thereby forming thetransparent conductive layer 340.

The transparent conductive layer 340 further increases thelight-scattering effect of the metal nanoparticles and protects themetal nanoparticles when the metal nanoparticles are exposed to highheat in a subsequent process.

The forming of the metal thin film (operation S10), the performing ofthe annealing process (operation S20), and the forming of thetransparent conductive layer (operation S30) may be repeatedly performedto form a light-scattering substrate having multiple transparentconductive layers and multiple light-scattering layers. In addition, atransparent conductive layer may be formed on a substrate before theforming of the metal thin film (operation S10), and a metal thin filmmay be formed on the transparent conductive layer.

Hereinafter, an organic light-emitting display device according to anexemplary embodiment of the present invention will be described withreference to FIG. 7.

FIG. 7 is a cross-sectional view of an organic light-emitting displaydevice according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the organic light-emitting display device accordingto the current exemplary embodiment includes a substrate 110,alight-scattering layer 120, a buffer layer 20, an active layer 30, agate insulating film 40, a gate electrode 41, an interlayer insulatingfilm 51, source and drain electrodes 52 and 53, respectively, apassivation layer 61, a first electrode 70, and a pixel defined layer80.

The substrate 110 may be appropriately selected by those of ordinaryskill in the art from a transparent substrate, a quartz substrate, aceramic substrate, a silicon substrate, and a flexible substrate madeof, e.g., plastic. If possible, the substrate 110 may be made of atransparent glass material containing SiO₂ as its main component. Theplastic may be an organic material selected from the group consisting ofpolyethyelenenapthalate, polyimide, polyallylate, polyphenylenesulfide,polyethersulphone, polyacrylate, polycarbonate,polyethyeleneterepthalate, polysulphone, polyetherimide,cellulosetriacetate, and celluloseacetatepropionate.

The light-scattering layer 120 is composed of metal nanoparticles formedby depositing a metal thin film on the entire surface of the substrate110 using a method such as sputtering or CVD and annealing the metalthin film. Since the organic light-emitting display device according tothe current exemplary embodiment includes the light-scattering layer 120composed of metal nanoparticles formed directly on the substrate 110,there is no need to insert a light-scattering sheet or film into theorganic light-emitting display device.

The light-scattering layer 120, composed of a plurality of metalnanoparticles which exhibit the surface plasmon phenomenon, scatterslight generated by an organic light-emitting layer (not shown) of theorganic light-emitting display device. The metal nanoparticles come invarious diameters, and can have any shape such as a circular or oval. Inaddition, the metal nanoparticles may overlap each other in multiplelayers. As the metal nanoparticles are formed, the substrate 110 may bepartially exposed. The metal nanoparticles may be formed to an averagediameter of 50 to 500 nm.

The buffer layer 20 forms a smooth surface on the substrate 110 andkeeps impurities from infiltrating into the substrate 110. The bufferlayer 20 may be made of any material which enables the buffer layer 20to perform the above function. If possible, the buffer layer 20 may bemade of SiO₂ and/or SiN_(x).

The buffer layer 20 is formed on the entire surface of the substrate 110so as to completely cover the light-scattering layer 120. That is, themetal nanoparticles of the light-scattering layer 120 are contained inthe buffer layer 20.

The active layer 30 is formed on the buffer layer 20 and may be made ofan inorganic semiconductor, such as amorphous silicon or polycrystallinesilicon, or an organic semiconductor. The active layer 30 includes achannel region 32 unimplanted with impurity ions and source and drainregions 31 and 33, respectively, disposed on both sides of the channelregion 32 and implanted with p- or n-type impurity ions. The impurityions may vary according to the type of transistor. For example, donorimpurity ions, such as P, As or Sb, may be injected to manufacture anN-type thin-film transistor (TFT). On the other hand, acceptor impurityions, such as B, Al, Ga or In, may be injected so as to manufacture aP-type TFT.

The gate insulating film 40 is formed on the entire surface of thesubstrate 110, the buffer layer 20, and the active layer 30. The gateinsulating film 40 may be formed using a conventional method known inthe art, such as CVD or plasma-enhanced chemical vapor deposition(PECVD). The gate insulating film 40 may be made of an inorganicmaterial, an organic material, or a mixture of the inorganic materialand the organic material. Examples of the inorganic material may includeSiO₂, SiN_(x), and SiON.

The gate electrode 41 is formed on the gate insulating film 40 andoverlaps the channel region 32 of the active layer 30. The gateelectrode 41 may be formed of a single layer of a material or a mixtureof materials selected from the group consisting of Mo, W, AlNd, Ti, Al,Ag, and an alloy of these materials. Alternatively, the gate electrode41 may be formed of a double- or multi-layer of Mo, Al or Ag, which is amaterial with low resistivity, in order to reduce wiring resistance.That is, to reduce wiring resistance, multiple conductive layers may besequentially stacked. Specifically, the gate electrode 41 may have amulti-layer structure composed of Mo/Al/Mo, MoW/AlNd/MoW, Mo/Ag/Mo,Mo/Ag alloy/Mo, or Ti/Al/Mo.

The interlayer insulating film 51 is formed on the gate insulating film40 so as to cover the gate electrode 41. An upper surface of theinterlayer insulating film 51 may be planar. Contact holes 54 and 55exposing the source and drain regions 31 and 33, respectively, of theactive layer 30 are formed in the interlayer insulating film 51.

The interlayer insulating film 51 may be formed of an inorganicinsulating film or an organic insulating film. Examples of the inorganicinsulating film which forms the interlayer insulating film 51 includeSiO₂, SiN_(x), SiON, Al₂O₃, TiO₂, Ta₂O₅, HfO₂, ZrO₂, BST and PZT, andexamples of the organic insulating film include general-purpose polymer(such as polymethylmethacrylate (PMMA) or polystyrene (PS)), polymerderivatives having a phenol group, acrylic polymer, imide polymer, arylether polymer, amide polymer, fluoride polymer, p-xylene polymer, vinylalcohol polymer, and a blend of these materials. Also, the interlayerinsulating film 51 may be formed of a stack of an inorganic insulatingfilm and an organic insulating film.

The source and drain electrodes 52 and 53, respectively, are formed onthe interlayer insulating film 51 and are connected to the source anddrain electrodes 31 and 33, respectively, of the active layer 30 by thecontact holes 54 and 55, respectively.

Each of the source and drain electrodes 52 and 53, respectively, may beformed of a single layer of a material or a mixture of materialsselected from the group consisting of Mo, W, MoW, AlNd, Ti, Al, Alalloy, Ag, and Ag alloy. Alternatively, each of the source and drainelectrodes 52 and 53, respectively, may be formed of a double- ormulti-layer of Mo, Al or Ag, which is a material with low resistivity,in order to reduce wiring resistance. That is, each of the source anddrain electrodes 52 and 53, respectively, may have a multi-layerstructure composed of Mo/Al/Mo, MoW/AlNd/MoW, Ti/Al/Ti, Mo/Ag/Mo, orMo/Ag alloy/Mo.

The passivation layer 61 is formed on the interlayer insulating film 51and the source and drain electrodes 52 and 53, respectively, and acontact hole 62 exposing any one of the source and drain electrodes 52and 53, respectively, is formed in the passivation layer 61. Thepassivation layer 61 may be formed of an inorganic insulating layer oran organic insulating layer.

The first electrode 70 is formed on the passivation layer 61 and isconnected to any one of the source and drain electrodes 52 and 53,respectively, by the contact hole 62. The first electrode 70 may beformed of a transparent conductive film containing one or moretransparent materials selected from ITO, IZO, ZnO, and In₂O₃.

The pixel defined layer 80 is formed on the passivation layer 61 andexposes the first electrode 70. The pixel defined layer 80 may be madeof a material or a mixture of materials selected from the groupconsisting of polyacrylic resin, epoxy rein, phenol resin, polyamideresin, polyimide resin, unsaturated polyester resin, polyphenyleneresin, polyphenylene sulfide resin, and benzocyclobutene.

Hereinafter, an organic light-emitting display device according toanother exemplary embodiment of the present invention will be describedwith reference to FIG. 8.

FIG. 8 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention.

The organic light-emitting display device according to the currentexemplary embodiment has the same configuration as the organiclight-emitting display device of FIG. 7, except that it includes atransparent conductive layer 130. The following description will focuson these differences, and elements substantially identical to those ofthe previous embodiment are indicated by like reference numerals, andthus a detailed description thereof will be omitted.

Referring to FIG. 8, the organic light-emitting display device accordingto the current exemplary embodiment includes a substrate 110, alight-scattering layer 120, a transparent conductive layer 130, a bufferlayer 20, an active layer 30, a gate insulating film 40, a gateelectrode 41, an interlayer insulating film 51, source and drainelectrodes 52 and 53, respectively, a passivation layer 61, a firstelectrode 70, and a pixel defined layer 80.

The transparent conductive layer 130 is formed on the substrate 110 andthe light-scattering layer 120 so as to cover the light-scattering layer120. Therefore, metal nanoparticles of the light-scattering layer 120are contained in the transparent conductive layer 130. The transparentconductive layer 130 increases the light-scattering effect of the metalnanoparticles of the light-scattering layer 120, and prevents the metalnanoparticles from agglomerating again when exposed to high heat in asubsequent process. The transparent conductive layer 130 may be made ofITO, IZO, ZnO, or In₂O₃.

The transparent conductive layer 130 may be formed to a thickness of 1to 50 nm. The transparent conductive layer 130 formed to a thickness inthe above range can further increase the light-scattering effect andenhance the thermal resistance of the organic light-emitting displaydevice.

In FIG. 8, each of the light-scattering layer 120 and the transparentconductive layer 130 is formed as a single layer. However, the presentinvention is not limited thereto. A second light-scattering layer (notshown) composed of metal nanoparticles may be formed by forming a metalthin film on the transparent conductive layer 130 and annealing themetal thin film, and a second transparent conductive layer (not shown)may be formed on the second light-scattering layer. This process may berepeatedly performed so as to manufacture an organic light-emittingdisplay device having multiple light-scattering layers and multipletransparent conductive layers.

Hereinafter, an organic light-emitting display device according toanother exemplary embodiment of the present invention will be describedwith reference to FIG. 9.

FIG. 9 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention.

The organic light-emitting display device according to the currentexemplary embodiment has the same configuration as the organiclight-emitting display device of FIG. 8, except that a light-scatteringlayer 120 and a transparent conductive layer 130 are formed under asubstrate 110. The following description will focus on thesedifferences, and elements substantially identical to those of theprevious embodiment are indicated by like reference numerals and thus adetailed description thereof will be omitted.

Referring to FIG. 9, the organic light-emitting display device accordingto the current exemplary embodiment includes the light-scattering layer120, the transparent conductive layer 130, the substrate 110, a bufferlayer 20, an active layer 30, a gate insulating film 40, a gateelectrode 41, an interlayer insulating film 51, source and drainelectrodes 52 and 53, respectively a passivation layer 61, a firstelectrode 70, and a pixel defined layer 80.

The light-scattering layer 120 is formed on a lower surface of thesubstrate 110 and composed of a plurality of metal nanoparticles. Thelight-scattering layer 120 is in the form of the metal nanoparticlesattached to the lower surface of the substrate 110. Since thelight-scattering layer 120 is formed directly on the substrate 110, themetal nanoparticles are attached to the substrate and all of the metalnanoparticles are connected to the substrate 110. The organiclight-emitting display device according to the current exemplaryembodiment has a bottom emission structure in which light is emitted inthe direction of the substrate 110. The substrate 110 may be made of atransparent material. As light is emitted through the substrate 110, itis scattered by the metal nanoparticles of the light-scattering layer120.

The transparent conductive layer 130 is formed under the substrate 110so as to be thicker than the light-scattering layer 120. Accordingly,the metal nanoparticles of the light-scattering layer 120 are containedwithin the transparent conductive layer 130.

Hereinafter, an organic light-emitting display device according toanother exemplary embodiment of the present invention will be describedwith reference to FIG. 10.

FIG. 10 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention.

The organic light-emitting display device according to the currentexemplary embodiment has the same configuration as the organiclight-emitting display device of FIG. 7, except that a light-scatteringlayer 140, a transparent conductive layer 141, an organic light-emittinglayer 71, and a second electrode 72 are formed on a first electrode 70.The following description will focus on these differences, and elementssubstantially identical to those of the previous embodiment areindicated by like reference numerals, and thus a detailed descriptionthereof will be omitted.

The light-scattering layer 140 is formed on the first electrode 70 andis composed of a plurality of metal nanoparticles. The metalnanoparticles are attached onto the first electrode 70 so as to form thelight-scattering layer 140. The organic light-emitting display deviceaccording to the current exemplary embodiment is a bottom emission typein which an image is formed in the direction of the substrate 110.Accordingly, the first electrode 70 may be made of a transparentmaterial. Light generated by the organic light-emitting layer 71 isscattered by the light-scattering layer 140 before passing through thefirst electrode 70.

The light-scattering layer 140 may be formed in the same way as thelight-scattering layer 120 of the organic light-emitting display deviceshown in FIG. 7. More specifically, the metal nanoparticles are formedby depositing a metal thin film on an exposed region of the firstelectrode 70 using a method such as sputtering or CVD, and annealing themetal thin film to induce the agglomeration of a metal of the metal thinfilm. The metal nanoparticles remain attached onto the first electrode70 and scatter light generated by the organic light-emitting layer 71.

The transparent conductive layer 141 is formed on the first electrode 70so as to be thicker than the light-scattering layer 140. Accordingly,the metal nanoparticles of the light-scattering layer 140 are containedin the transparent conductive layer 141. The transparent conductivelayer 141 may be made of ITO, IZO, ZnO or In₂O₃, and the metalnanoparticles increase the light-scattering effect. The transparentconductive layer 141 may be omitted as desired by those of ordinaryskill in the art. The organic light-emitting layer 71 can also be formedimmediately on the light-scattering layer 140.

The organic light-emitting layer 71 is formed on the transparentconductive layer 141 and emits light in response to the electricaldriving of the first electrode 70 and the second electrode 72. Theorganic light-emitting layer 71 may be made of a low or high molecularweight organic material. When the organic light-emitting layer 71 ismade of a low molecular weight organic material, a hole transport layerand a hole injection layer are stacked in the direction of the firstelectrode 70 with respect to the organic light-emitting layer 71, and anelectron transport layer and an electron injection layer are stacked inthe direction of the second electrode 72 with respect to the organiclight-emitting layer 71. Also, various layers, other than the abovelayers, may be stacked as desired. Examples of the organic materialinclude, but are not limited to, copper phthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB),tris-8-hydroxyquinoline aluminum (Alq3).

When the organic light-emitting layer 71 is a high molecular weightorganic layer made of a high molecular weight organic material, only ahole transport layer may be formed in the direction of the firstelectrode 70 with respect to the organic light-emitting layer 71. Thehole transport layer is formed of poly-(2,4)-ethylene-dihydroxythiophene(PEDOT) or polyaniline (PANI) on the first electrode 70 by using aninkjet printing or spin coating method. Polyphenylene vinylene (PPV),soluble PPV's, cyano-PPV, or polyfluorene may be used for the organiclight-emitting layer 71. In addition, a color pattern may be formedusing a conventional method, such as inkjet printing, spin coating, orthermal transfer using a laser.

The second electrode 72 is formed on the organic light-emitting layer71. In the organic light-emitting display device according to thecurrent exemplary embodiment, the first electrode 70 is used as an anodeelectrode, and the second electrode 72 is used as a cathode electrode.However, the polarities of the first and second electrodes 70 and 71,respectively, can also be reversed. When the organic light-emittingdisplay device is a bottom emission type in which an image is formed inthe direction of the substrate 110, the first electrode 70 is atransparent electrode, and the second electrode 72 is a reflectiveelectrode. The second electrode 72 may be made of a metal having a smallwork function, such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, orCa. A sealant (not shown) may further be provided on the secondelectrode 72 in order to protect the organic light-emitting layer 71from external moisture or oxygen.

Hereinafter, an organic light-emitting display device according toanother exemplary embodiment of the present invention will be describedwith reference to FIG. 11.

FIG. 11 is a cross-sectional view of an organic light-emitting displaydevice according to another exemplary embodiment of the presentinvention.

The organic light-emitting display device according to the currentexemplary embodiment has the same configuration as the organiclight-emitting display device of FIG. 7, except that no light-scatteringlayer is formed on a substrate 110 while a light-scattering layer 150and a transparent conductive layer 160 are formed on a second electrode72. The following description will focus on these differences, andelements substantially identical to those of the previous embodiment areindicated by like reference numerals, and thus a detailed descriptionthereof will be omitted.

The light-scattering layer 150 is formed on the second electrode 72.Like the light-scattering layers 120 and 140 shown in FIG. 10, thelight-scattering layer 150 is composed of a plurality of metalnanoparticles attached onto the second electrode 72. The organiclight-emitting display device according to the current exemplaryembodiment is a top emission type in which an image is formed in anopposite direction of the substrate 110. In the top emission organiclight-emitting display device, the second electrode 72 is a transparentelectrode, and the first electrode 70 is a reflective electrode.Therefore, there is no need to form a light-scattering layer on or underthe substrate 110. Light generated by the organic light-emitting layer71 passes through the second electrode 72 and is scattered by the metalnanoparticles of the light-scattering layer 150.

The transparent conductive layer 160 is formed on the second electrode72, and may be formed of the same material as the second electrode 72.The transparent conductive layer 160 is formed on the second electrode72 so as to be thicker than the light-scattering layer 150, and themetal nanoparticles, of the light-scattering layer 150 are contained inthe transparent conductive layer 160. The transparent conductive layer160 increases the light-scattering effect of the metal nanoparticles andmay be omitted as desired by those of ordinary skill in the art.

As described above, an organic light-emitting display device accordingto the present invention includes a light-scattering layer formeddirectly on a substrate. Therefore, no light-scattering film or sheet isneeded. In addition, the light-scattering layer is not in the form of anorganic or inorganic layer into which light-scattering particles havebeen inserted. Instead, the light-scattering layer is in the form ofmetal nanoparticles attached directly onto the substrate. This structureis advantageous to the thinning of the organic light-emitting displaydevice, and enables the organic light-emitting display device to exhibitsuperior thermal resistance.

A light-scattering substrate according to the present invention can beused not only in the above organic light-emitting display device, butalso in optical devices and apparatuses such as liquid crystal displays(LCDs).

An LCD includes a TFT substrate having TFTs, a substrate facing the TFTsubstrate, and a liquid crystal layer interposed between the twosubstrates. A light-scattering substrate according to an exemplaryembodiment of the present invention may be used as the TFT substrate orthe substrate facing the TFT substrate in the LCD. When thelight-scattering substrate, in which a light-scattering layer accordingto an exemplary embodiment of the present invention is formed directlyon a substrate, is used as the TFT substrate or the substrate facing theTFT substrate, there is no need to install a light-scattering film.Metal nanoparticles attached onto the light-scattering substrate scatterlight incident upon a panel, thereby making a display screen bright andcapable of displaying a clear image.

When the substrate is made of resin, the light-scattering substrateaccording to the present invention may be inserted into an LCD or anorganic light-emitting display device in the form of a film or sheet.

A backlight (or transmissive) LCD includes a liquid crystal cell and abacklight unit placed behind the liquid crystal cell and providing lightto the liquid crystal cell. The liquid crystal cell includes a pair ofsubstrates (a TFT substrate and a substrate facing the TFT substrate)and a liquid crystal layer interposed between the substrates. Thebacklight unit includes a light source, and a light guide plate (LGP)and a reflective plate which guide light emitted from the light sourceto the liquid crystal cell. A light-scattering substrate according toexemplary embodiments of the present invention can be placed at anyposition. For example, the light-scattering substrate may be disposedbetween the LGP and the liquid crystal cell, on a surface of the LGP, ona rear surface of the liquid crystal cell, or on a surface of the liquidcrystal cell.

A reflective LCD includes a liquid crystal cell and a reflector which isplaced behind the liquid crystal cell and reflects incident light. Alight-scattering substrate according to exemplary embodiments of thepresent invention can be placed at any position as long as it is locatedin front of the reflector. In a TFT LCD, a light-scattering substrateaccording to exemplary embodiments of the present invention may bepositioned between a substrate facing a TFT substrate and a polarizingfilm. However, the light-scattering substrate can be placed at anyposition.

An organic light-emitting display device comprises a display panel whichincludes a cathode formed on a surface of a substrate, an organicelectroluminescent layer, and an anode. A light-scattering substrateaccording to exemplary embodiments of the present invention may bedisposed on a surface of the substrate, but can be placed at anyposition.

Hereinafter, a method of manufacturing an organic light-emitting displaydevice according to an exemplary embodiment of the present inventionwill be described with reference to FIGS. 12 thru 23.

FIGS. 12 thru 23 are cross-sectional views respectively illustratingprocesses in a method of manufacturing an organic light-emitting displaydevice according to an exemplary embodiment of the present invention.

Referring to FIG. 12, a metal thin film 121 is deposited on a substrate110.

The substrate 110 may be made of a glass material having SiO₂ as itsmain component. However, the present invention is not limited thereto.That is, the substrate 110 may be made of various materials, such as aplastic material. However, since the organic light-emitting displaydevice according to the current exemplary embodiment is a bottomemission type in which an image is formed in the direction of thesubstrate 110, the substrate 110 must be made of a transparent material.

The metal thin film 121 may be deposited on the substrate 110 using,e.g., sputtering or CVD. The metal thin film 121 may be made of a metalwhich can agglomerate on the substrate 110 during an annealing processdue to its high surface energy, among metals showing the surface plasmonphenomenon. Specifically, the metal thin film 121 may be made of Ag, Au,a mixture of Ag and Au, or an alloy of Ag or Au and one or more of Cu,Ni, Co, Fe, Zn, Ti, Cr, Pt, Al and Pd. Here, the Ag or Au may be addedat 80 wt % or more based on a total weight of the alloy. When added at80 wt % or more, the Ag or Au can agglomerate into metal nanoparticlesand exhibits a superior light-scattering effect.

Referring to FIGS. 12 and 13, a light-scattering layer 120 is formed byannealing the metal thin film 121. The annealing process may beperformed using a thermal annealing method using a furnace, a laserannealing method, or an RTA method. In addition, the annealing processmay be performed at a temperature of 200 to 350° C. for one hour in theatmosphere of an inert gas such as air or nitrogen. The conditions underwhich the annealing process is performed can be arbitrarily changed bythose of ordinary skill in the art. If possible, however, the annealingprocess may be performed at a temperature of 200 to 350° C. When themetal thin film 121 is annealed, the metal which forms the metal thinfilm 121 agglomerates into a plurality of metal nanoparticles attachedonto the substrate 110. In addition, as the metal agglomerates into themetal nanoparticles, the substrate 110 is partially exposed. The methodof forming the light-scattering layer 120 is the same as theabove-described method of manufacturing a light-scattering substrate,and thus a detailed description thereof is omitted.

Referring to FIG. 14, a buffer layer 20 is formed on the substrate 110so as to form a smooth surface on the substrate 110 and prevent theinfiltration of impurity elements into the substrate 110. To form thebuffer layer 20, SiO₂ and/or SiN_(x) may be deposited using variousmethods such as PECVD, atmospheric pressure CVD (APCVD), and lowpressure CVD (LPCVD). Since the buffer layer 20 is formed on thesubstrate 110 so as to be thicker than the light-scattering layer 120,the metal nanoparticles of the light-scattering layer 120 are containedin the buffer layer 20.

Referring to FIG. 15, an active layer 30 is formed by stacking asemiconductor layer on the buffer layer 20 and patterning thesemiconductor layer. The semiconductor layer may be made of amorphoussilicon or polycrystalline silicon. The patterning process may be aphotolithography process using a mask. The polycrystalline silicon maybe deposited directly on the buffer layer 20. Alternatively, after theamorphous silicon is deposited, it may be crystallized using variousmethods, such as an RTA method, a solid phase crystallization (SPC)method, an excimer laser annealing (ELA) method, a metal inducedcrystallization (MIC) method, a metal induced lateral crystallization(MILC) method, and a sequential lateral solidification (SLS) method.

Referring to FIG. 16, a gate insulating film 40 is formed by depositingan insulating material on the buffer layer 20 and the active layer 30using sputtering or CVD. The gate insulating film 40 may be made of aninorganic material, an organic material, or a mixture of the inorganicmaterial and the organic material. Examples of the inorganic materialmay include SiO₂, SiN_(x), and SiON.

Referring to FIG. 17, a conductive film for forming a gate electrode isformed on the gate insulating film 40 using, e.g., sputtering and isthen patterned, thereby forming a gate electrode 41 which overlaps achannel region 32 of the active layer 30.

The conductive film may be formed of a single layer of a material or amixture of materials selected from the group consisting of Mo, W, AlNd,Ti, Al, Ag, and an alloy of these materials. Alternatively, theconductive film may be formed of a double- or multi-layer of Mo, Al orAg, which is a material with low resistivity, in order to reduce wiringresistance.

Referring to FIG. 18, the active layer 30, including the channel region32 and source and drain regions 31 and 33, respectively, is formed byimplanting N- or P-type impurities using the gate electrode 41 as amask. The channel region 32 serves as a passage for electrons and isunimplanted with impurities. The source and drain regions 31 and 33,respectively, are formed by implanting impurities into both sides of thechannel region 32. For example, donor impurity ions, such as P, As orSb, may be injected so as to manufacture an N-type TFT. On the otherhand, acceptor impurity ions, such as B, Al, Ga or In, may be injectedso as to manufacture a P-type TFT.

Referring to FIG. 19, an interlayer insulating film 51 is formed on thegate insulating film 40 so as to be higher than the gate electrode 41relative to the substrate 110. The interlayer insulating film 51 may beformed by sputtering or CVD and may be formed of two or more layers asdesired by those of ordinary skill in the art. Each layer in thismulti-layer structure may be formed to various thicknesses as desired bythose of ordinary skill in the art. In addition, a topmost interlayerinsulating film in the multi-layer structure may be formed to have aplanar top surface. The interlayer insulating film 51 may be formed ofan inorganic insulating film, an organic insulating film, or a compositeof the inorganic insulating film and the organic insulating film.

Contact holes 54 and 55, exposing the source and drain regions 31 and33, respectively, of the active layer 30 may be formed in the interlayerinsulating film 51 by a photolithography process. Here, the interlayerinsulating film 51 may be dry-etched or wet-etched.

Referring to FIG. 20, a conductive film for forming source and drainelectrodes is formed on the interlayer insulating film 51 so as to fillthe contact holes 54 and 55, respectively, and is then patterned,thereby forming source and drain electrodes 52 and 53, respectively.

Referring to FIG. 21, a passivation layer 61 is formed on the interlayerinsulating film 51 so as to cover the source and drain electrodes 52 and53, respectively. Specifically, the passivation layer 61 is formed bydepositing an organic material or an inorganic material on theinterlayer insulating film 51 using sputtering or CVD. In addition, acontact hole 62 exposing a region of any one of the source and drainelectrodes 52 and 53, respectively, is formed in the passivation layer61. The contact hole 62 may be formed by a photolithography processusing a mask. Here, a wet-etching or dry-etching process may beperformed.

Referring to FIG. 22, a conductive film for forming a first electrode isdeposited on the passivation layer 61 using sputtering or CVD so as tofill the contact hole 62. Then, the conductive film is patterned by aphotolithography process, thereby forming a first electrode 70. Sincethe organic light-emitting display device according to the currentexemplary embodiment is a bottom emission type, the first electrode 70is formed to be a transparent electrode.

Referring to FIG. 23, a material for forming a pixel defined layer isdeposited on the passivation layer 61 and the first electrode 70 using,e.g., CVD. Then, the material is patterned to expose a region of thefirst electrode 70. As a result, a pixel defined layer 80 is formed. Thepixel defined layer 80 not only defines a light-emitting region but alsowidens the gap between an edge of the first electrode 70 and a secondelectrode 72. The widened gap prevents an electric field from beingconcentrated on the edge of the first electrode 70, thereby averting ashort circuit between the first electrode 70 and the second electrode72.

A metal thin film is deposited on the region of the first electrode 70which is exposed by the pixel defined layer 80. Then, the metal thinfilm is annealed to form a plurality of nanoparticles attached to a topsurface of the first electrode 70. Accordingly, a light-scattering layercomposed of the metal nanoparticles is formed on the first electrode 70.The light-scattering layer may be formed in the same way as theabove-described light-scattering layer 120. In addition, a transparentconductive layer may be formed on the light-scattering layer on thefirst electrode 70 so as to contain the metal nanoparticles of thelight-scattering layer.

As described above, in the method of manufacturing an organiclight-emitting display device according to the present invention, alight-scattering layer is formed directly on a substrate. Therefore, anorganic light-emitting display device having a superior light-scatteringeffect can be manufactured.

Hereinafter, effects of a light-scattering substrate according to anexemplary embodiment of the present invention will be described ingreater detail by way of example. The following example is intended as adetailed description of the present invention, but does not limit thescope of the present invention.

EXAMPLE Haze Measurement

An alloy of Ag, Pd, and Cu was deposited to a predetermined thickness ona glass substrate and annealed at 250° C. for one hour in the presenceof N₂ to form metal nanoparticles. Then, haze with respect to thethickness of a thin film of the Ag—Pd—Cu alloy was measured, and themeasurement results are shown in FIG. 24.

FIG. 24 is a graph illustrating haze with respect to the thickness of alight-scattering layer of a light-scattering substrate according to anexemplary embodiment of the present invention.

As shown in FIG. 24, a metal thin film formed to a thickness of 100 to200 Å shows a high haze value, and larger metal nanoparticles result inhigher haze values. In the case of a metal thin film formed to athickness of approximately 150 Å, for example, an average diameter ofmetal nanoparticles is approximately 400 nm.

In a method of manufacturing a light-scattering substrate according toan exemplary embodiment of the present invention, metal nanoparticlescan be formed directly on a substrate so that they are attached to atleast a surface of the substrate.

In a light-scattering substrate according to an exemplary embodiment ofthe present invention, metal nanoparticles attached onto a substratebring about a light-scattering effect. Therefore, there is no need toinsert light-scattering particles into a film or sheet.

A light-scattering substrate according to an exemplary embodiment of thepresent invention can be thinned since it does not require a film orsheet for accommodating light-scattering particles.

A light-scattering substrate according to an exemplary embodiment of thepresent invention exhibits superior thermal resistance, and itsproperties do not change even when the light-scattering substrate isexposed to high heat in a subsequent process for manufacturing a displaydevice which includes the light-scattering substrate.

A light-scattering substrate according to an exemplary embodiment of thepresent invention can be used in place of a substrate in LCDs or organiclight-emitting display devices. When a light-scattering substrateaccording to an exemplary embodiment is used as a substrate of a displaydevice, there is no need to install a light-scattering sheet or film.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetail may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Theexemplary embodiments should be considered in a descriptive sense only,and not for purposes of limitation.

What is claimed is:
 1. An organic light-emitting display device,comprising: a first light-scattering layer including metal nanoparticleswhich are attached to a surface of a transparent substrate; a bufferlayer formed on the transparent substrate so as to contain the metalnanoparticles; an active layer formed on the buffer layer and includinga channel region, a source region, and a drain region; a gate insulatingfilm formed on the transparent substrate and the active layer; a gateelectrode formed on the gate insulating film so as to overlap thechannel region; an interlayer insulating film formed on the gateinsulating film so as to cover the gate electrode, and including contactholes which expose predetermined regions of the source region and thedrain region, respectively; source and drain electrodes formed on theinterlayer insulating film and connected to the source region and drainregions, respectively, by the contact holes; a passivation layer formedon the interlayer insulating film so as to cover the source region anddrain electrodes; a first electrode formed on the passivation layer, andconnected to one of the source and drain electrodes; and a pixel definedlayer formed on the passivation layer, and exposing a predeterminedregion of the first electrode; the metal nanoparticles showing a surfaceplasmon phenomenon, and the metal nanoparticles are formed by stacking ametal thin film on the substrate and annealing the metal thin film so asto agglomerate a metal of the metal thin film.
 2. The display device ofclaim 1, the metal nanoparticles are made of an alloy of Ag, Pd, and Cu.3. The display device of claim 1, the buffer layer comprising atransparent conductive layer formed on the substrate so as to containthe metal nanoparticles.
 4. The display device of claim 1, furthercomprising a second light-scattering layer formed on the first electrodeand including a plurality of metal nanoparticles which are attached to atop surface of the first electrode.
 5. The display device of claim 4,further comprising a transparent conductive layer formed on the firstelectrode so as to contain the metal nanoparticles of the secondlight-scattering layer.
 6. An organic light-emitting display device,comprising: an active layer formed on a substrate and including achannel region, a source region and a drain region; a gate insulatingfilm formed on the substrate and the active layer; a gate electrodeformed on the gate insulating film so as to overlap the channel region;an interlayer insulating film formed on the gate insulating film so asto cover the gate electrode, and including first contact holes whichexpose the source region and the drain region, respectively; source anddrain electrodes formed on the interlayer insulating film and connectedto the source region and the drain region, respectively, by the firstcontact holes; a passivation layer formed on the interlayer insulatingfilm and including a second contact hole which exposes one of the sourceand drain electrodes; a first electrode formed on the passivation layerand connected to one of the source and drain electrodes by the secondcontact hole; a pixel defined layer formed on the passivation layer andexposing a predetermined region of the first electrode; an organiclight-emitting layer formed on the predetermined region of the firstelectrode which is exposed by the pixel defined layer; a transparentsecond electrode formed on the pixel defined layer and the organiclight-emitting layer; and a light-scattering layer including a pluralityof metal nanoparticles which are attached to a top surface of the secondelectrode; the metal nanoparticles showing a surface plasmon phenomenon,and the metal nanoparticles are formed by stacking a metal thin film onthe top surface of the second electrode and annealing the metal thinfilm so as to agglomerate a metal of the metal thin film.
 7. The displaydevice of claim 6, further comprising a transparent conductive layerformed on the second electrode so as to contain the metal nanoparticles.